Is describing someone as a "baltagy" an insult and a moral assault, taking into consideration the non-Arabic origin of the word?

The word "balṭajī" (thug) is conventionally considered an insult, even though its origin is not Arabic. Scholars have stipulated that if a word is conventionally used for cursing or slandering, then convention is to be relied upon. A Muslim should avoid such words and accustom his tongue to good speech, in obedience to Allah's saying: "And tell My servants to say that which is best. Indeed, Satan incites [discord] among them."